Molecular and Crystal Structure Diversity, and Physical Properties of Tetrathiafulvalene Derivatives Substituted with Various Aryl Groups through Sulfur Bridges

Abstract

A library of tetrathiafulvalene (TTF) derivatives (TTF-1-TTF-47) bearing aryl groups attached through sulfur bridges has been created. The peripheral aryl groups exert a significant influence on both the electronic and crystallographic properties of the resulting TTFs. These TTFs display broad absorption bands at 400-500 nm caused by intramolecular charge-transfer transitions between the aryl groups and central TTF core, and their first redox potentials increase with increasing electron-withdrawing ability of the aryl groups. In their crystal structures (22 examples), the central TTF cores adopt various conformations, including chair, half-chair, boat, and planar conformations. Moreover, the peripheral aryl groups exhibit multiple alignment modes with respect to the central TTF core, caused by their rotation about the two C-S bonds of the sulfur bridges. The packing motifs of these TTFs depend on both the nature of the aryl groups and their spatial alignment modes. Driven by intermolecular van der Waals forces and π-π interactions between the aryl groups and between the aryl groups and the TTF core, these TTFs adopt various packing structures. As a typical example, TTF-14, an achiral molecule, adopts a helical chain stack through intermolecular atomic close contacts. Moreover, the molecular geometries and packing motifs of these TTFs are sensitive to environmental variation, as exemplified by TTF-28, which adopts three distinct crystal modifications with diverse molecular geometries and stacking modes under different crystallization conditions. This work indicates that these TTFs are potential candidates as electronic materials, as well as functional building blocks for supramolecular assembly.

Organic–Inorganic Hybrid Clusters Assembled from Phosphomolybdate Anions and Thioarylated Tetrathiafulvalenes with Diversiform Electron States and Configurations

“…The central TTF core in TTF1 adopts a planar conformation with the central C=C lengths (1.37 and 1.39 Å) close to that of a TTF cation radical . The molecular geometry of TTF1 in the clusters, both in terms of spatial alignment of the phenyl groups and the central TTF core conformation, is very different to that of its neutral crystalline form in CS 2 . The PMA anion is surrounded by four TTF1 molecules (Figure b), and most of the phenyl groups of TTF1 are close to PMA.…”

“…In the proton‐induced intermolecular charge‐transfer method, the oxidation ability of unsaturated organic compounds of PMA was initially considered. According to the redox potential of the TTFs (E 1 ox = 0.48–0.68 V) and PMA (E 1 re = –0.27 V),[10m] intermolecular charge transfer would occur, i.e., TTF + H 3 PMo 12 O 40 → [TTF] + · + [H 2 PMo V Mo VI 11 O 40 ] – . However, this phenomenon was not observed by ESR analysis, where the g value for Mo V should be 1.948.…”

Copper ion salts of arylthiotetrathiafulvalenes: synthesis, structure diversity and magnetic properties

“…The donor molecules ( 1 – 7 , Scheme 1) were synthesized according to our previous report [37–38], and their electrochemical activities as well as the crystal structures have been fully elucidated [38–39]. Since the redox potentials of TTFs are very important in the formation of complexes, particularly on the charge-transfer degree, the first ( E 1/2 1 ) and the second ( E 1/2 2 ) redox potentials of 1 – 7 are summarized in Table 1.…”

“…Tetrahydrofuran (THF) and acetonitrile (CH 3 CN) were distilled over CaH 2 and stored under N 2 atomsphere. Compounds 1 – 7 were synthesized by following our previous reports [37–38]. …”

“…Recently, we have disclosed a facile approach toward Ar-S-TTFs [37]. Crystallographic investigations indicate that Ar-S-TTFs show various molecular geometries and packing structures depending on the nature of the peripheral aryls [38–39]. …”